The role of paratransit: some reflections based on the experience of residents’ coach services in Hong Kong

Paratransit refers to urban transport services “somewhere between private passenger transport and conventional public transport in terms of cost and quality of service” [Rimmer (1980), Paratransit: A commentary. Environ. Plan. A 12, 937–944]. Since the 1980s, a new form of paratransit—residents’ coach, which provides exclusive transport services to residents living in private housing estates—has emerged in Hong Kong. What was the background underlying the emergence and subsequent growth of residents’ coach services? Also, what was the role of residents’ coach in the public transport system of Hong Kong? With the completion of more railway extensions, should residents’ coach services be replaced? If so, what are the potential impacts on people’s life? This paper addresses the above research questions through a large-scale questionnaire survey that examined not only people’s modal choice but also their residential choice, socio-economic background and attitudes. The findings suggest that transport policy makers should pay more attention to examine new forms of paratransit and the ways of integrating them into the overall public transport system, both spatially and temporally. It is only through the development of an efficient and multi-modal transport system can the maximum potential of paratransit in filling the transport gap between conventional mass transit and private cars be realized.     

Experimental study of lightweight expanded polystyrene aggregate concrete containing silica fume and polypropylene fibers

We developed a new structural lightweight concrete by totally or partially replacing coarse and fine aggregates in high performance concrete by expanded polystyrene (EPS) beads. In this work,the sizes of EPS bead were 1.0,2.5 and 6.3 mm. Lightweight EPS concretes with a wide range of concrete densities and compressive strengths were successfully developed. Compressive strength,splitting tensile strength,shrinkage,and water absorption were examined. Additionally,fine silica fume (SF) and polypropylene (PP) f...     

Mesh motion approach based on spring analogy method for unstructured meshes

Mesh motion strategy is one of the key points in many fluid-structure interaction problems. One popular technique used to solve this problem is known as the spring analogy method. In this paper a new mesh update approach based on the spring analogy method is presented for the effective treatment of mesh moving boundary problems. The proposed mesh update technique is developed to avoid the generation of squashed invalid elements and maintain mesh quality by considering each element shape and grid scale to th...     

H_∞ Autopilot Design for Autonomous Underwater Vehicles

The design approach of H∞ autopilot for autonomous underwater vehicles (AUVs) is proposed. Comprised by the three sub-controllers,i.e. speed,heading and depth controllers,the designed autopilot has advantage over existing H∞ control of AUVs. The overshoot in speed,heading and depth control systems under step commands is restricted by refining the weighting function for robust stability. The dynamic performance of heading and depth control systems is improved by feeding back yaw rate and pitch angle,respecti...     

Method for workspace calculation of 6R serial manipulator based on surface enveloping and overlaying

Aiming at the workspace calculation problem of multi-joint serial manipulators, a surface enveloping and overlaying (SEO) method is presented to identify and visualize the manipulator workspace. The SEO method is composed of two stages: the first stage is to choose reference points of the manipulator and calculate their boundary surfaces using the nth enveloping method; the second stage is to overlay these boundary surfaces to identify the final workspace. The SEO method is basically a combination of the analytic method and the numerical method. By delineating the graphic representation of the workspace step by step, the SEO method is easy to analyze the existence and the shape of voids and holes. The basic theory of the SEO method and formulas for workspace calculation are presented based on a 6R serial manipulator. By showing the workspace calculation results, the SEO method is proved working correctly.     

Mechanical behaviors of the foot after individual releases of plantar fascia and ligaments during the balanced standing

To quantify mechanical effects of plantar fascia and ligaments on the arch structure, a 3D finite element model of the foot was created to simulate the balanced standing posture. Four cases after individual releases of plantar fascia, spring ligament, long and short plantar ligaments were simulated respectively to compare their consequences to the predictions of the intact structure. It was founded that the foot arch didn’t collapse obviously after any individual release of these structures. As plantar fascia was released, tensions of plantar ligaments were largely increased. Long and short plantar ligaments performed mutual compensation functions.     

Fuzzy optimization of storage space allocation in a container terminal

A fuzzy optimization model of storage space allocation is proposed, and a rolling-planning method is derived. The model takes the uncertainty of departure time of import containers and arrival time of export containers into account. For each planning horizon, the problem is decomposed into two levels: the first level minimizes the unbalanced workloads among blocks using hybrid intelligence algorithm; based on block workloads allocated in the above level, the second level minimizes the number of blocks to which the same group of import containers are split. Numerical results show that the model reduces workload imbalance, and speeds up the vessel loading and discharging process.     

Initial conditions of impact dynamics

The effects of the initial conditions of impact dynamics equations are investigated numerically and experimentally. The inadequacies of previous studies on initial conditions are pointed out. Then a coefficient of velocity jump at the moment of impact is introduced, and the experiments for the mental rods are implemented to validate the appending constraints modeling methods for impact process. The comparisons between the experimental and simulated results at different coefficients are used to study the effects of the velocity jump conditions to the numerical simulation. The results indicate that the physical velocity response of bodies during impact is smooth; the different values of velocity jump only have small effects on numerical oscillation of velocity response, and they have no effects on the time history of impact force.     

Dynamic investigation on composite flexible multi-body system considering thermal effect

The dynamic performance of composite flexible multi-body system under the simultaneous action of thermal fields and driving constraint is analyzed. Based on strain-displacement relation of the Mindlin plate theory which includes transverse shear deformation, and considering thermal effect, variation equations of laminated plate are derived by the principle of virtual work. The finite element method is used for discretization. According to kinematics constraint relation, dynamic equations for spatial slider-crank system are established. Simulation results show that spatial deformation (torsion deformation) appears in the multi-layered composite slider-crank mechanism which is simulated with planar motions. Furthermore, the influence of coupling between thermal expansion and flexible deformations of non-symmetrical composite plates on the large overall motion under the uniform temperature field is investigated. Finally, significant change in constraint force due to the spatial deformation is shown.     

Numerical implementation of meshless method for electromagnetic field governing equations

For electromagnetic governing equations formulated by magnetic vector potential and electric scalar potential, its detailed numerical implementation is achieved by using meshless method and Galerkin approach. And essential boundary and interface condition of electromagnetic field are imposed by means of Lagrange multiplier method. Furthermore, the influences of interpolation point number at essential boundary and interface on computational results are also discussed. Examples are given to validate the effects of meshless method and Lagrange multiplier approach for electromagnetic field.